The most common fastening systems of conventional electrical motor driven nail guns are described below:
The first design uses solenoid driven mechanisms. One of the drawbacks of these types of mechanisms is that the force provided by a solenoid is governed by the number of ampere-turns in the solenoid. In order to obtain the high forces required for driving nails and staples into the work piece, a large number of turns are required in addition to high current pulses. These requirements are counterproductive as the resistance of the coil increases in direct proportion to the length of the wire in the solenoid windings. This design limits most solenoid driven mechanisms to short stroke small load applications.
A second design is based on a multiple impact design. In this design, a motor or other power source is connected to the impact anvil through either a lost motion coupling or other. This allows the power source to make multiple impacts on the nail thus driving it into the working piece. The disadvantages in this design that include increased operator fatigue since the actuation technique is a series of blows rather than a continuous drive motion.
A third design which is taught includes the use of spring as energy storage mechanisms. In these designs, once the spring is sufficiently compressed, the energy is released from the spring into the anvil (or nail driving piece) thus pushing the nail into the substrate. Several drawbacks exist to this design. These include the need for a complex system of compressing and controlling the spring and the fact that the force delivery characteristics of a spring are not well suited for driving nails. As the nail is driven into the wood, more force is needed as the stroke increases. This is inherently backwards to a spring's unloading scheme in which it delivers less force as it returns to its zero energy state.
A fourth design that is taught includes the using a flywheel to store energy to drive a fastener; this design is detailed in British Patent #2,000,716. This patent teaches me use of a continuously rotating mechanism. The disadvantages in this design include increased operator fatigue by the noisy, continuously rotating mechanism. Also, this uses a friction clutch mechanism that is complicated, heavy and subject to wear.
A fifth design uses flywheels as energy storage means. The flywheels are used to launch a hammering anvil that impacts the nail. This design is detailed in U.S. Pat. No. 6,604,666B1. The major drawback to this design is that the flywheels and the clutch mechanisms are asynchronous. The complete mechanism is complicated and a memory of rotating position. It shows that all energy is stored in the flywheel when the rotation angle is within 150 degree. If the operator launches the trigger when the rotation angle is less than 100 degree or if caused by an obstacle, so that the driving of the anvil that impacts the nail is not completed, when the trigger is launched again, the fly wheel will only rotate a 50 degree angle, so that the power which is stored in the fly wheel is not strong enough to drive the nail into the work piece. So it requires design of a complicated circuit to control additional rotating mechanisms (counter rotating), which allow the motor to counter-rotate the 100 degrees to reach the 0 degree (initially location).
A sixth design, U.S. Pat. No. 6,705,503B1, shows that a longer guide rail is very important to prevent the moving pin jamming the solenoid and cam system. A drawback to this design is not self-resetting. Once the operator launches the trigger, if the mechanism is stopped in the middle location of the guide rail, and then the trigger is launched again, the power source of the action from the middle location to the end is not strong enough to effect a normal driving of the anvil that impacts the nail. So it needs an additional rotation mechanism (counter rotating) to get the motor back to initial location, and its additional action causes unwanted time for operator.
All the currently available devices suffer from a number of disadvantages that include:    1. Solenoid driven mechanisms limit large current, and don't provide a good effect of driving (impact on the nail).    2. Multiple impact design causes increased operator fatigue.    3. Mechanisms in the form of spring do not wear well since the spring doesn't have a predictable rated lifetime.    4. It's hard to hold the tool still when a flywheel mechanism is continuously rotating, and wastes unnecessary user energy.    5. Flywheels and cam hold asynchronous clutch mechanisms are complicated and require memory of rotational position. It needs a complicated circuit to control the additional rotating mechanism (counter rotating). This counter-rotating action is unnecessary to the principal task.    6. A longer guide rail holds up the pin and also needs a memory of the rotating state. It also needs a complicated circuit to control the additional rotating mechanism (counter rotating). The action is unwanted and not easy to operate.